1. Field
The present invention relates to a communication technique, and in particular, to a terminal device, a communication system, and a communication method for executing a call for communication.
2. Description of the Related Art
It is desirable to enable group communication through mobile stations located in a designated area without taking a time for setting the group communication. Accordingly, each mobile station acquires positional information on its own by an incidental GPS (Global Positioning System) receiver. A control office transmits a call signal for the group communication by adding area information on a mobile station that is a target of the group communication. The mobile station receives the group communication from the control office when the positional information on its own and the area information in the call signal match each other (for example, Patent Document 1).
[Patent Document 1] Japanese Patent Application Publication No. 2009-177639
Because positional information is generally indicated by latitude and longitude, area information to be compared with the positional information is also indicated by them. On the other hand, it is more desirable that a call of group communication in a desired area is simpler.